1. What is the circulatory system?
Lesson 12
What is the circulatory system?

2. Can you imagine being a messenger that makes trillions of stops in just 30 seconds????
Your blood does!
Blood is an important body messenger. It is on the move day and night.

3. In just 30 seconds, your blood moves or circulates through your whole body. It reaches out to all of your trillions of cells.
Blood transports (carries) to the cells all the things it needs.
What do your cells need?

4. Cells need things like:
oxygen
digested foods
The cells absorb or take in these materials.

5. The blood is also your body’s trash collectors.
What type of things are made in the cells that need to be taken out with the trash?
heat
carbon dioxide
extra water

6. The blood picks up these waste materials from the cells and takes them to places that get them out of the body. (we will talk about that later in the year)

7. Blood is pumped throughout the body by the heart
Blood is pumped throughout the body by the heart. It flows through a closed system of tubes, called blood vessels.
Your body has three types of blood vessels.

8. Arteries:
-carry blood away from the heart
-carry the materials the cells need
-except the arteries going to the lungs carry blood rich in oxygen and nutrients

9. Veins:
-carry blood from the body back to the heart
-except the veins coming from the lungs, veins carry blood with dissolved waste products

10. Capillaries:
-connect arteries and veins
-are microscopic
-most of the blood vessels in your body are capillaries

11. The heart, blood vessels, and blood make up your circulatory system.
Circulation, or transport, is a vital function. Life can not go on without it.